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Anonymous Poster

Short time current withstand calculation for busbars

05/20/2010 4:31 AM

is K2S2 = I2t (K square S square = I square t) a correct formula for calculating the busbar cross section using short time current value?for example i have 40kA overcurrent for duration of 3 sec for a copper busbar and i want to have the cross section.

if it is a correct formula,what is K??i know its some kind of constant related to insulation and installation type and material etc., consider copper busbar and connected using bolts and nuts.
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kvsridhar
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#1

Re: short time current withstand calculation for busbars

05/20/2010 5:12 AM

The cross section will decide the thermal withstand capability of the busbar, what about the ability to withstand the dynamic forces due to the asymmetric peak which appears on the first half-cycle ? That will depend on the supports mainly. You may get some useful information here : Schneider-electric ect158.pdf

There are also some threads on CR4, you can browse them too.

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msamad
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#2
In reply to #1

Re: short time current withstand calculation for busbars

05/20/2010 9:20 PM

Here is another formula to caculate it.

http://www.copperinfo.co.uk/busbars/pub22-copper-for-busbars/sec6.htm

- MS

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kvsridhar
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#3
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Re: short time current withstand calculation for busbars

05/20/2010 9:41 PM

Good link. GA

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sridharganasen
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#4
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Re: short time current withstand calculation for busbars

05/21/2010 7:35 AM

thanks for your information very good link
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